/Engine/Plugins/FX/Niagara/Source/NiagaraEditor/Public/NiagaraNodeAssignment.h
This will rename an existing input but will not refresh the underlying script. RefreshFromExternalChanges must be called if this function returns true.
bool RenameAssignmentTarget ( [FName](API\Runtime\Core\UObject\FName) OldName, [FName](API\Runtime\Core\UObject\FName) NewName )